Communication control device and communication control method

Abstract

The present invention provides a communication control device and a communication control method that enable load balancing between base station devices while suppressing quality degradation at terminal devices. [Solution] The system includes an information receiving unit that receives quality information indicating the communication quality and load information indicating the communication load for each of a specific cell and a plurality of adjacent cells from a base station device; a cell identification unit that identifies one of the plurality of cells as the first cell on which a terminal device located in the specific cell will perform a handover at a predetermined timing, based on the load information and quality information for each of the plurality of cells at a predetermined timing; and an information transmitting unit that transmits information indicating the identified first cell to the base station device.

Description

Technical Field

[0001] The present invention relates to a communication control device and a communication control method.

Background Art

[0002] In recent years, as one of the SON (Self-Organizing Networks) technologies in a wireless communication system, a mobility load balancing (MLB) technology has emerged that switches the base station device to which a terminal device connects according to the load state of each base station device (see, for example, Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described load distribution between base station devices, for example, the load state in each base station device is used as a criterion for balancing judgment. Therefore, in the above-described load distribution between base station devices, for example, the communication quality in the terminal device may deteriorate.

[0005] Therefore, in one aspect, an object of the present invention is to provide a communication control device and a communication control method that enable load distribution between base station devices while suppressing deterioration in quality in a terminal device.

Means for Solving the Problems

[0006] A communication control device in one embodiment includes: an information receiving unit that receives quality information indicating the communication quality and load information indicating the communication load for each of a specific cell and a plurality of adjacent cells from a base station device; a cell identification unit that identifies one of the plurality of cells as a first cell on which a terminal device located in the specific cell will perform a handover at the predetermined timing, based on the load information and quality information for each of the plurality of cells at a predetermined timing; and an information transmitting unit that transmits information indicating the identified first cell to the base station device. [Effects of the Invention]

[0007] From one perspective, this makes it possible to distribute the load between base station devices while suppressing quality degradation at terminal devices. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram illustrating the configuration of the wireless communication system 10. [Figure 2] Figure 2 is a diagram illustrating the configuration of the wireless communication system 10. [Figure 3] Figure 3 illustrates a specific example of load balancing performed by the communication control device 3 on each base station device 1. [Figure 4] Figure 4 is a diagram illustrating the hardware configuration of base station equipment 1. [Figure 5] Figure 5 is a diagram illustrating the hardware configuration of terminal device 2. [Figure 6] Figure 6 is a diagram illustrating the hardware configuration of the communication control device 3. [Figure 7] Figure 7 is a diagram illustrating the functions of the base station device 1 in the first embodiment. [Figure 8] Figure 8 is a diagram illustrating the functions of the terminal device 2 in the first embodiment. [Figure 9]FIG. 9 is a diagram for explaining the functions of the communication control device 3 in the first embodiment. [Figure 10] FIG. 10 is a sequence chart of the communication control process in the first embodiment. [Figure 11] FIG. 11 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 12] FIG. 12 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 13] FIG. 13 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 14] FIG. 14 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 15] FIG. 15 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 16] FIG. 16 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 17] FIG. 17 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 18] FIG. 18 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 19] FIG. 19 is a flowchart for explaining the details of the communication control process in the first embodiment. [Figure 20] FIG. 20 is a diagram for explaining a specific example of the performance information DT2. [Figure 21] FIG. 21 is a diagram for explaining the details of the communication control process in the first embodiment. [Figure 22] FIG. 22 is a diagram for explaining the details of the communication control process in the first embodiment. [Figure 23] FIG. 23 is a diagram for explaining a specific example of the policy information DT3. [Figure 24] FIG. 24 is a diagram for explaining a specific example of the measurement information DT1. [Figure 25] FIG. 25 is a diagram for explaining a specific example of the aggregation information DT4a. [Figure 26] FIG. 26 is a diagram for explaining a specific example of the aggregation information DT4b. [Figure 27] FIG. 27 is a diagram for explaining details of the communication control process in the first embodiment. [Figure 28] FIG. 28 is a diagram for explaining details of the communication control process in the first embodiment. [Embodiments for Carrying Out the Invention]

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, such description should not be construed in a limiting sense and does not limit the subject matter described in the claims. Also, various changes, substitutions, and modifications can be made without departing from the spirit and scope of the present disclosure. Further, different embodiments can be combined as appropriate.

[0010] [Configuration of the Wireless Communication System in the First Embodiment] First, the configuration of the wireless communication system 10 will be described. FIGS. 1 and 2 are diagrams for explaining the configuration of the wireless communication system 10.

[0011] As shown in FIG. 1, the wireless communication system 10 includes, for example, a base station device 1a, a base station device 1b, and a terminal device 2. Hereinafter, the base station device 1a and the base station device 1b are collectively referred to simply as the base station device 1.

[0012] As shown in FIG. 1, the base station device 1a forms, for example, a cell Ca. The base station device 1b forms, for example, a cell Cb. Hereinafter, the cell Ca and the cell Cb are collectively referred to simply as the cell C. In the example shown in FIG. 1, the terminal device 2 is located, for example, within the cell Ca and makes a wireless connection with the base station device 1a.

[0013] The wireless communication system 10 may be, for example, a wireless communication system that supports the communication standards of the 5th Generation Mobile Communication System (5G) or the next generation communication standards of the 5th Generation Mobile Communication System. The terminal device 2 may be, for example, a smartphone owned by an individual, or an IoT device installed outdoors. Furthermore, although the following description assumes that one terminal device 2 is located in cell Ca, cell Ca may contain, for example, other numbers of terminal devices 2. Furthermore, although the following description assumes that no terminal devices 2 are located in cell Cb, cell Cb may contain, for example, one or more terminal devices 2. Furthermore, although the following description assumes that the wireless communication system 10 has two base station devices 1, the wireless communication system 10 may contain, for example, other numbers of base station devices 1.

[0014] Furthermore, as shown in Figure 2, the wireless communication system 10 includes, for example, a base station device 1 and a terminal device 2, as well as a communication control device 3.

[0015] The communication control device 3 is, for example, one or more physical or virtual machines, and performs processing to control communication between the base station device 1 and the terminal device 2, as well as load balancing on each base station device 1 (hereinafter also referred to as communication control processing). The following describes a specific example of load balancing on each base station device 1 performed by the communication control device 3.

[0016] [Specific examples of load balancing] Figure 3 illustrates a specific example of load balancing performed by the communication control device 3 on each base station device 1. In the following explanation, cell Ca and cell Cb shown in Figure 3 correspond to cell Ca and cell Cb described in Figure 1, respectively.

[0017] In the example shown in Figure 3, cells Cb, Cc, Cd, Ce, and Cf are all located around cell Ca. Hereafter, other cells C located around cell C will also be referred to as adjacent cells C.

[0018] Furthermore, in the example shown in Figure 3, at the boundary between cell Ca, cell Cb, and cell Cc, there exists a competitive area Aa, which is an area where wireless connections can be established with, for example, base station equipment 1a corresponding to cell Ca, base station equipment 1b corresponding to cell Cb, and base station equipment 1 corresponding to cell Cc. Similarly, at the boundary between cell Ca, cell Cc, and cell Cd, there exists a competitive area Ab, for example. Also, at the boundary between cell Ca, cell Cd, cell Ce, and cell Cf, there exists a competitive area Ac, for example. Hereinafter, competitive areas Aa, Ab, and Ac will be collectively referred to simply as competitive area A.

[0019] Then, when a user possessing terminal device 2 (hereinafter also simply referred to as "user") moves from cell Ca to cell Cb, and the user passes through the competition area Aa, the communication control device 3 selects, for example, one of cell Ca, cell Cb, or cell Cc as cell C to establish a wireless connection with terminal device 2 while moving through the competition area Aa.

[0020] Specifically, as shown in Figure 3, if the load in cells Ca and Cb is higher than that of other cells C, including cell Cc, the communication control device 3 will, for example, select cell Cc, which has a lower load than cells Ca and Cb, as the cell to connect to when terminal device 2 passes through the conflict area Aa. That is, in this case, terminal device 2 will, for example, perform a handover (HO) from cell Ca to cell Cc in response to a user moving from cell Ca (an area in cell Ca other than the conflict area Aa) to the conflict area Aa, and further perform a handover from cell Cc to cell Cb in response to a user moving from the conflict area Aa to cell Cb (an area in cell Cb other than the conflict area Aa).

[0021] This enables the communication control device 3 to perform load balancing between each base station device 1, for example.

[0022] In the load balancing shown in Figure 3, for example, the load state at each base station device 1 is used as the criterion for determining the balance. Therefore, in the load balancing shown in Figure 3, for example, the communication quality at terminal device 2 may deteriorate.

[0023] Therefore, the communication control device 3 in this embodiment receives, for example, quality information (hereinafter simply referred to as quality information) indicating the communication quality and load information (hereinafter simply referred to as load information) indicating the communication load for each of the multiple adjacent cells C adjacent to the cell C to be processed (hereinafter also referred to as target cell C or specific cell C). Then, for example, for each of the multiple adjacent cells C, the communication control device 3 in this embodiment calculates a reference value (hereinafter simply referred to as reference value) that indicates the upper limit of the load information that satisfies a condition (hereinafter also referred to as the first condition) for the quality information in each adjacent cell C, based on the quality information and load information corresponding to each adjacent cell C. The first condition is, for example, that the value indicated by the quality information does not fall below a predetermined threshold.

[0024] Next, the communication control device 3 in this embodiment identifies, for example, one or more adjacent cells C (hereinafter also simply referred to as one or more adjacent cells C) among a plurality of adjacent cells C whose load information at a predetermined timing is below a reference value, and identifies one of the adjacent cells C among the identified one or more adjacent cells C as the cell C (hereinafter also referred to as the first cell C or HO destination cell C) on which the terminal device 2 located at the target cell C will perform a handover at a predetermined timing. The predetermined timing is, for example, the timing after the reference value has been calculated. After that, the communication control device 3 in this embodiment transmits, for example, information indicating the identified HO destination cell C to the base station device 1 corresponding to the target cell C.

[0025] In other words, the communication control device 3 in this embodiment selects, for example, the adjacent cell C (HO destination cell C) to which the terminal device 2 will hand over in the competition area A from among adjacent cells C that can be determined to be capable of maintaining the minimum necessary communication quality.

[0026] As a result, the communication control device 3 in this embodiment can, for example, perform load balancing between each base station device 1 while suppressing quality degradation at the terminal device 2.

[0027] [Hardware configuration of wireless communication system] Next, the hardware configuration of the wireless communication system 10 will be explained. Figure 4 is a diagram illustrating the hardware configuration of the base station device 1. Figure 5 is a diagram illustrating the hardware configuration of the terminal device 2. Figure 6 is a diagram illustrating the hardware configuration of the communication control device 3.

[0028] First, the hardware configuration of the base station device 1 will be described. As shown in Figure 4, the base station device 1 includes, for example, a CPU (Central Processing Unit) 101, a memory 102, a communication circuit 103, and a storage device 104. Each part is connected to the others via a bus 105.

[0029] The storage device 104 has, for example, a program storage area (not shown) for storing a program (not shown) for performing communication control processing. The storage device 104 also has, for example, a storage unit 130 (hereinafter also referred to as the information storage area 130) for storing information used when performing communication control processing. The storage device 104 may be, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0030] The CPU 101, for example, executes a program loaded from the storage device 104 into memory 102 to perform communication control processing.

[0031] The communication circuit 103 includes, for example, a circuit that communicates wirelessly with the terminal device 2 via the antenna 106. The communication circuit 103 also includes, for example, a circuit that communicates via a wired connection with the communication control device 3.

[0032] Next, the hardware configuration of terminal device 2 will be described. As shown in Figure 5, terminal device 2 includes, for example, a processor CPU 201, memory 202, a communication circuit 203, and a storage device 204. Each part is connected to the others via a bus 205.

[0033] The storage device 204 has, for example, a program storage area (not shown) for storing a program 210 for performing communication control processing. The storage device 204 also has, for example, a storage unit 230 (hereinafter also referred to as the information storage area 230) for storing information used when performing communication control processing. The storage device 204 may be, for example, an HDD or an SSD.

[0034] The CPU 201, for example, executes the program 210 loaded from the storage device 204 into memory 202 to perform communication control processing.

[0035] The communication circuit 203 has, for example, a circuit that communicates by making a wireless connection with the base station device 1 via the antenna 206.

[0036] Next, the hardware configuration of the communication control device 3 will be described. As shown in Figure 6, the communication control device 3 includes, for example, a processor CPU (Central Processing Unit) 301, a memory 302, a communication circuit 303, and a storage device 304. Each part is connected to the others via a bus 305.

[0037] The storage device 304 has, for example, a program storage area (not shown) for storing a program (not shown) for performing communication control processing. The storage device 304 also has, for example, a storage unit 330 (hereinafter also referred to as the information storage area 330) for storing information used when performing communication control processing. The storage device 304 may be, for example, an HDD or an SSD.

[0038] The CPU 301, for example, executes a program loaded from the storage device 304 into memory 302 to perform communication control processing.

[0039] The communication circuit 303 includes, for example, a circuit that communicates with the base station device 1 via a wired connection.

[0040] [Functions of the communication system in the first embodiment] Next, the functions of the wireless communication system 10 in the first embodiment will be described. Figure 7 is a diagram illustrating the functions of the base station device 1 in the first embodiment. Figure 8 is a diagram illustrating the functions of the terminal device 2 in the first embodiment. Figure 9 is a diagram illustrating the functions of the communication control device 3 in the first embodiment.

[0041] [Functions in base station equipment] First, we will explain the functions of base station device 1.

[0042] As shown in Figure 7, the base station device 1 implements various functions, including a signal receiving unit 111, a signal transmitting unit 112, an information generating unit 113, an information transmitting unit 114, and an information receiving unit 115, through the organic cooperation of hardware such as a CPU 101 and memory 102 with a program.

[0043] The signal receiving unit 111 receives signals (hereinafter also referred to as uplink signals) transmitted from the terminal device 2 via, for example, the antenna 106. The uplink signals include, for example, uplink control signals and uplink data signals. The uplink control signals are transmitted, for example, by PUCCH (Physical Uplink Control Channel). The uplink data signals are transmitted, for example, by PUSCH (Physical Uplink Shared Channel).

[0044] Specifically, the signal receiving unit 111 receives a signal (uplink control signal) containing measurement information DT1 transmitted from the terminal device 2, for example. The measurement information DT1 is information indicating measurement results such as the signal reception quality (RSRP: Reference Signal Received Power) at the terminal device 2. The measurement information DT1 is also called a Measurement Report, for example. Then, as shown in Figure 7, the signal receiving unit 111 stores the measurement information DT1 contained in the received signal in the information storage area 130, for example.

[0045] The signal transmission unit 112 transmits a signal (downlink signal) to the terminal device 2, for example, via the antenna 106. The downlink signal includes, for example, a downlink control signal and a downlink data signal. The downlink control signal is transmitted, for example, by a PDCCH (Physical Downlink Control Channel). The downlink data signal is transmitted, for example, by a PDSCH (Physical Downlink Shared Channel).

[0046] The information generation unit 113 generates performance information DT2, which includes quality information and load information for cell C corresponding to its own device (base station device 1). Performance information DT2 is also called PM (PerforMance) data. Specifically, the information generation unit 113 generates performance information DT2, which includes quality information and load information for the time period since the last generation of performance information DT2, at predetermined intervals. Then, as shown in Figure 7, the information generation unit 113 stores the generated performance information DT2 in the information storage area 130.

[0047] The information transmission unit 114 transmits, for example, the measurement information DT1 received by the signal receiving unit 111 to the communication control device 3. The information transmission unit 114 also transmits, for example, the performance information DT2 generated by the information generation unit 113 to the communication control device 3.

[0048] The information receiving unit 115 receives, for example, policy information DT3 transmitted from the communication control device 3. The policy information DT3 includes information that includes a policy used, for example, when determining the handover destination cell C (HO destination cell C) for terminal devices 2 located within the cell C corresponding to its own device (base station device 1). The information receiving unit 115 then stores the received policy information DT3 in the information storage area 130.

[0049] [Functions in terminal devices] Next, we will explain the functions of terminal device 2.

[0050] As shown in Figure 8, the terminal device 2 implements various functions, including a signal receiving unit 211, an information generation unit 212, and a signal transmission unit 213, through the organic cooperation of hardware such as the CPU 201 and memory 202 with the program 210.

[0051] The signal receiving unit 211 receives, for example, downlink signals transmitted from the base station device 1 via the antenna 206.

[0052] The information generation unit 212 generates, for example, measurement information DT1 for its own device (terminal device 2). Specifically, the information generation unit 113 generates, for example, measurement information DT1 for the time period since the last generation of measurement information DT1 at predetermined intervals. The information generation unit 212 then stores the generated measurement information DT1 in the information storage area 130.

[0053] The signal transmission unit 213 transmits an uplink signal to the base station device 1, for example, via the antenna 206.

[0054] Specifically, the signal transmission unit 213 transmits a signal (uplink control signal) including the measurement information DT1 generated by the information generation unit 212 to the base station device 1.

[0055] [Functions in communication control devices] Next, we will explain the functions of the communication control device 3.

[0056] As shown in Figure 9, the base station device 1 implements various functions, including an information receiving unit 311, an information generating unit 312 (hereinafter also referred to as a reference calculation unit 312), a cell identification unit 313, a power calculation unit 314, and an information transmission unit 315, through the organic cooperation of hardware such as a CPU 301 and memory 302 with a program.

[0057] The following description will focus on the case where various functions, including the information receiving unit 311, information generating unit 312, cell identification unit 313, power calculation unit 314, and information transmission unit 315, are implemented in a single communication control device 3, but this is not limited to that case. Specifically, the various functions, including the information receiving unit 311, information generating unit 312, cell identification unit 313, power calculation unit 314, and information transmission unit 315, may be implemented in a distributed manner across multiple communication control devices 3, for example.

[0058] The information receiving unit 311 receives performance information DT2 from multiple base station devices 1 corresponding to each of the multiple adjacent cells C, for example. Then, as shown in Figure 9, the information receiving unit 311 stores each of the received performance information DT2 in the information storage area 330.

[0059] The information generation unit 312 calculates a reference value for each of the multiple adjacent cells C, based on the quality information and load information contained in the performance information DT2 (performance information DT2 stored in the information storage area 130) corresponding to each adjacent cell C, which indicates the upper limit of the load information for which the quality information in each cell C satisfies the first condition. The information generation unit 312 then generates policy information DT3, which includes the calculated reference value. Subsequently, the information generation unit 312 stores the generated policy information DT3 in the information storage area 330.

[0060] Furthermore, quality information may include, for example, information indicating the communication quality status of terminal devices 2 located within each cell C, or information (values) calculated using the information indicating the communication quality status of terminal devices 2 located within each cell C, which is included in the performance information DT2. Specifically, quality information may include, for example, the success rate of establishing RRC (Radio Resource Control) connections in each cell C, or the success rate of handovers to each cell C. Also, quality information may include, for example, the information included in measurement information DT1.

[0061] Furthermore, the load information may include, for example, information indicating the load status in each cell C, or information (values) generated from the information indicating the load status in each cell C, which is included in the performance information DT2. Specifically, the load information may include, for example, the RRC connection rate in each cell C or the cell throughput rate in each cell C.

[0062] The cell identification unit 313 identifies, for example, one or more adjacent cells C from among a plurality of adjacent cells C whose load information at a predetermined timing is below a reference value, and based on the quality information corresponding to each of the identified one or more adjacent cells C, it identifies one of the adjacent cells C as the cell C (HO destination cell C) on which the terminal device 2 located at the target cell C will perform a handover at a predetermined timing.

[0063] The power calculation unit 314 calculates the transmission power to the terminal device 2 in the HO destination cell C, for example, according to the quality information of the HO destination cell C identified by the cell identification unit 313.

[0064] The information transmission unit 315 transmits, for example, the policy information DT3 generated by the information generation unit 312 to the base station device 1 corresponding to the target cell C. The information transmission unit 315 also transmits, for example, information indicating the HO destination cell C identified by the cell identification unit 313 (hereinafter also referred to as cell information) to the base station device 1 corresponding to the target cell C. The information transmission unit 315 also transmits, for example, information indicating the transmission power calculated by the power calculation unit 314 to the base station device 1 corresponding to the target cell C.

[0065] The following explanation describes a case where a reference value is calculated that indicates the upper limit of load information for which the quality information in each cell C satisfies the first condition, and one or more adjacent cells C whose load information at a predetermined timing is below the reference value are identified, but is not limited to this case. Specifically, the information generation unit 312 may, for example, calculate other reference values ​​(hereinafter simply referred to as other reference values) for each of the multiple adjacent cells C that indicate the lower limit of quality information for which the quality information in each cell C satisfies the first condition. The cell identification unit 313 may, for example, identify one or more adjacent cells C whose quality information at a predetermined timing is above the other reference value.

[0066] [Sequence chart diagram of communication control processing in the first embodiment] Next, a sequence chart of the communication control process in the first embodiment will be described. Figure 10 is a sequence chart of the communication control process in the first embodiment.

[0067] As shown in Figure 10, the communication control device 3 receives performance information DT2 for each of the multiple adjacent cells C adjacent to the target cell C (S1).

[0068] Then, the communication control device 3 calculates a reference value corresponding to each of the multiple adjacent cells C based on the quality information and load information contained in the performance information DT2 received in S1 (S2).

[0069] Next, the communication control device 3 identifies, for example, one or more adjacent cells C from among a plurality of adjacent cells C whose load information at a predetermined timing is less than or equal to the reference value calculated in S2, and based on the quality information corresponding to each of the identified one or more cells C, it identifies one of the one or more adjacent cells C as the HO destination cell C on which the terminal device 2 located at the target cell C will perform a handover at a predetermined timing (S3).

[0070] Subsequently, the communication control device 3 transmits, for example, information (cell information) indicating the HO destination cell C identified in S3 to the base station device 1 corresponding to the target cell C (S4).

[0071] In other words, the communication control device 3 in this embodiment selects, for example, the adjacent cell C (HO destination cell C) to which the terminal device 2 will hand over in the competition area A from among adjacent cells C that can be determined to be capable of maintaining the minimum necessary communication quality.

[0072] As a result, the communication control device 3 in this embodiment can, for example, perform load balancing between each base station device 1 while suppressing quality degradation at the terminal device 2.

[0073] [Details of the communication control process in the first embodiment] Next, the details of the communication control process in the first embodiment will be described. Figures 11 to 19 are flowcharts illustrating the details of the communication control process in the first embodiment. Figures 20 to 28 are diagrams illustrating the details of the communication control process in the first embodiment.

[0074] The following explanation will describe the case where the wireless communication system 10 has two communication control devices 3. Specifically, the following explanation will assume that the first communication control device 3 (also called communication control device 3a or first communication control device 3a) has an information receiving unit 311 (hereinafter also called information receiving unit 311a), an information generating unit 312, and an information transmitting unit 315 (hereinafter also called information transmitting unit 315a). Furthermore, the following explanation will assume that the second communication control device 3 (hereinafter also called communication control device 3b or second communication control device 3b) has an information receiving unit 311 (hereinafter also called information receiving unit 311b), a cell identification unit 313, a power calculation unit 314, and an information transmitting unit 315 (hereinafter also called information transmitting unit 315b). Furthermore, the information storage area 330 of communication control device 3a will also be referred to as information storage area 330a, and the information storage area 330 of communication control device 3b will also be referred to as information storage area 330b.

[0075] [Performance information storage processing in the first communication control device] First, we will explain the process of storing performance information DT2 (hereinafter also referred to as the performance information storage process) within the communication control device 3a. Figure 11 is a flowchart illustrating the performance information storage process.

[0076] As shown in Figure 11, the information receiving unit 311a waits until it receives performance information DT2 transmitted from, for example, the base station device 1 (NO in S11).

[0077] Specifically, the information receiving unit 311a waits, for example, until the base station device 1 transmits performance information DT2 using the O1 interface defined in 3GPP (Third Generation Partnership Project) (registered trademark).

[0078] Then, if performance information DT2 is received (YES in S11), the information receiving unit 311a stores the received performance information DT2 in the information storage area 330a, for example (S12). A specific example of performance information DT2 will be explained below.

[0079] [Specific performance details] Figure 20 illustrates a specific example of performance information DT2.

[0080] As shown in Figure 20, the performance information DT2 includes, for example, "DL Total PRB Usage" and "UL Total PRB Usage" as defined in 3GPP TS28.552, which are set as "PRB Usage Rate". Additionally, the performance information DT2 includes, for example, "Mean number of RRC Connections" as defined in 3GPP TS28.552, which are set as "Number of Connected Users".

[0081] Furthermore, the performance information DT2 includes, for example, "Average delay DL air-interface" and "Average delay UL on over the air-interface" as defined in 3GPP TS28.552, which are set as "Average delay". Also, the performance information DT2 includes, for example, "Average DL UE throughput in gNB" and "Average UL UE throughput in gNB" as defined in 3GPP TS28.552, which are set as "Average throughput". Explanations of other information included in Figure 20 are omitted.

[0082] [Policy generation process in the first communication control device] Next, we will explain the process of generating policy information DT3 (hereinafter also referred to as the policy generation process) within the communication control device 3a. Figure 12 is a flowchart illustrating the policy generation process.

[0083] As shown in Figure 12, the information generation unit 312 waits, for example, until the first information generation timing occurs (NO in S21). The first information generation timing is, for example, a regular timing such as every 10 minutes.

[0084] Then, when the first information generation timing arrives (YES in S21), the information generation unit 312 determines a policy for each of the multiple cells C controlled by the communication control device 3a (hereinafter also simply referred to as multiple cells C) based on the performance information DT2 corresponding to each cell C (performance information DT2 stored in the information storage area 330a) (S22).

[0085] Specifically, in S22, the policy for each cell C is determined to be either "quality priority," which prioritizes ensuring communication quality at the terminal devices 2 located in each cell C over load balancing at the base station device 1 corresponding to each cell C, or "distribution priority," which prioritizes load balancing at the base station device 1 corresponding to each cell C over ensuring communication quality at the terminal devices 2 located in each cell C. The details of S22 will be explained below.

[0086] [Details of S22] Figure 18 is a flowchart illustrating the details of S22. The following explanation will cover the case where S22 is performed for cell Ca.

[0087] As shown in Figure 18, the information generation unit 312 determines, for example, whether a policy corresponding to cell Ca has been pre-set by the administrator of the wireless communication system 100 (hereinafter also simply referred to as the administrator) (S101).

[0088] As a result, if it is determined that a policy has been pre-configured by the administrator (YES in S101), the information generation unit 312 terminates, for example, S22. That is, in this case, the information generation unit 312 uses, for example, the policy pre-configured by the administrator as the policy corresponding to cell Ca, from S23 onward.

[0089] On the other hand, if the administrator determines that no policy has been set in advance (NO in S101), the information generation unit 312 determines, for example, whether the load state of cell Ca satisfies predetermined conditions (hereinafter also simply referred to as predetermined conditions) based on the performance information DT2 corresponding to cell Ca (performance information DT2 stored in the information storage area 330a) (S102).

[0090] Specifically, the information generation unit 312 determines that the load state of cell Ca satisfies a predetermined condition if, for example, the value set for "PRB usage rate" included in the performance information DT2 (hereinafter also referred to as the first value) is equal to or greater than a predetermined threshold (hereinafter also referred to as the first threshold).

[0091] Furthermore, the information generation unit 312 determines that the load state of cell Ca satisfies a predetermined condition if, for example, the value calculated by dividing the value set in "number of connected users" included in performance information DT2 by the maximum number of terminal devices 2 that can be accommodated in cell Ca (a predetermined value) (hereinafter also referred to as the second value) is equal to or greater than a predetermined threshold (hereinafter also referred to as the second threshold).

[0092] The information generation unit 312 may, for example, determine that the load state of cell Ca satisfies a predetermined condition when the first value is equal to or greater than the first threshold and the second value is equal to or greater than the second threshold.

[0093] Then, if it is determined that the load state of cell Ca meets a predetermined condition (YES in S102), the information generation unit 312 determines, for example, that the policy corresponding to cell Ca is "load priority" (S103).

[0094] In other words, in this case, the information generation unit 312 determines, for example, that cell Ca is in a high-load state and decides to prioritize load balancing in the base station device 1 (base station device 1a) corresponding to cell Ca.

[0095] On the other hand, if it is determined that the load state of cell Ca does not meet the conditions (NO in S102), the information generation unit 312, for example, decides on a policy corresponding to cell Ca to "quality priority" (S103).

[0096] In other words, in this case, the information generation unit 312 determines, for example, that cell Ca is in a low-load state and decides to prioritize ensuring communication quality at the terminal device 2 located within cell Ca.

[0097] Returning to Figure 12, the information generation unit 312 calculates a reference value for each of the multiple cells C based on the performance information DT2 corresponding to each cell C (S23). The details of S23 will be explained below.

[0098] [Details of S23] Figure 19 is a flowchart illustrating the details of S23. The following explanation will cover the case where S23 is performed on cell Ca.

[0099] The information generation unit 312 generates load information and quality information from each piece of information contained in each performance information DT2 (performance information DT2 stored in the information storage area 330a) corresponding to cell Ca, for example (S111).

[0100] Specifically, the information generation unit 312 calculates load information (hereinafter also referred to as cell load rate) using values ​​calculated from each piece of information indicating the load state in cell Ca, such as the RRC connection rate and cell throughput rate in cell Ca, which are included in the performance information DT2 corresponding to cell Ca. More specifically, the information generation unit 312 calculates load information by taking the average and maximum values ​​of each of the values ​​calculated using each piece of information indicating the load state in cell Ca.

[0101] Furthermore, the information generation unit 312 calculates quality information (hereinafter also referred to as the cell quality rate) using values ​​calculated from each piece of information in the performance information DT2 corresponding to cell Ca that indicates the communication quality status of the terminal device 2 located within cell Ca (for example, the success rate of establishing an RRC connection in cell Ca and the success rate of handover). More specifically, the information generation unit 312 calculates the average and maximum values ​​of each of the values ​​calculated using each piece of information that indicates the communication quality status of the terminal device 2 located within cell Ca as quality information.

[0102] Then, the information generation unit 312 obtains, for example, an initial value (not shown) of the reference value stored in the information storage area 330a (S112). The initial value of the reference value may be, for example, one that has been previously stored in the information storage area 330a by the administrator.

[0103] Furthermore, the information generation unit 312 acquires, for example, a quality tolerance value (not shown) stored in the information storage area 330a (S113). The quality tolerance value may be, for example, the minimum tolerance value for quality information in the terminal device 2, which is stored in the information storage area 330a in advance by the administrator.

[0104] Subsequently, the information generation unit 312 calculates a reference value (updated value) from the initial reference value obtained in S112 and the minimum allowable value obtained in S113, for example, by using an approximate straight line of points corresponding to the quality information and load information calculated in S111 (S114).

[0105] Specifically, as shown in Figure 21, the information generation unit 312 plots, for example, points corresponding to the quality information and load information calculated in S111 on a two-dimensional plane where the X and Y axes correspond to load information and quality information, where the quality information is less than the quality tolerance value (Y in Figure 21). Then, the information generation unit 312 calculates, for example, an approximate straight line L1 of the plotted points. Subsequently, the information generation unit 312 calculates, for example, a reference value (X in Figure 21) corresponding to the quality tolerance value (Y in Figure 21) on the calculated approximate straight line L1.

[0106] Furthermore, as shown in Figure 22, the information generation unit 312 plots points corresponding to the quality information and load information calculated in S111 on a two-dimensional plane where the X and Y axes correspond to the load information and quality information, respectively, where the quality information is equal to or greater than the quality tolerance value (Y in Figure 22). The information generation unit 312 then calculates, for example, an approximate straight line L2 of the plotted points. Subsequently, the information generation unit 312 calculates, for example, a reference value (X in Figure 22) corresponding to the quality tolerance value (Y in Figure 22) on the calculated approximate straight line L2.

[0107] The information generation unit 312 may calculate the reference value by, for example, preferentially using the approximation line with the larger absolute value of its slope (in the example shown in Figures 21 and 22), which is the approximation line L1, among the approximation lines L1 and L2.

[0108] Furthermore, the information generation unit 312 may, for example, determine the initial value of the reference value as the reference value if the reference value calculated using the approximate line L1 or approximate line L2 is smaller than the initial value of the reference value.

[0109] Returning to Figure 12, the information generation unit 312 generates policy information DT3 for each of the multiple cells C, for example, which includes the policy calculated in S22 and the reference value calculated in S23 (S24).

[0110] Then, the information transmission unit 315 transmits the policy information DT3 generated in S24 to the base station device 1 corresponding to each cell C, for example, for each of the multiple cell Cs (S25). A specific example of the policy information DT3 will be described below.

[0111] [Policy details specific examples] Figure 23 illustrates a specific example of policy information DT3. Specifically, Figure 23 illustrates a specific example of policy information DT3 generated for cell Ca. In the following, cells Ca, Cb, Cc, Cd, Ce, and Cf, as described in Figure 3, will also be simply referred to as Ca, Cb, Cc, Cd, Ce, and Cf.

[0112] As shown in Figure 23, the policy information DT3 includes items such as "Cell," which contains information indicating each cell C, and "Policy," which contains the policy used to determine the handover destination cell C (HO destination cell C) for terminal devices 2 located within each cell C. Furthermore, as shown in Figure 23, the policy information DT3 also includes an item called "Reference Value," which contains reference values ​​corresponding to each adjacent cell C within each cell C.

[0113] Specifically, in the policy information DT3 shown in Figure 23, for example, "Ca" is set as the "cell", "Quality Priority" is set as the "policy", "90(%)" is set as the "benchmark value" corresponding to "Cb", "85(%)" is set as the "benchmark value" corresponding to "Cc", "80(%)" is set as the "benchmark value" corresponding to "Cd", "75(%)" is set as the "benchmark value" corresponding to "Ce", and "70(%)" is set as the "benchmark value" corresponding to "Cf".

[0114] [Policy update processing in the second communication control unit] Next, we will explain the process of updating policy information DT3 (hereinafter also referred to as the policy update process) within the communication control device 3b. Figure 13 is a flowchart illustrating the policy update process.

[0115] As shown in Figure 13, the information receiving unit 311b waits until it receives, for example, the policy information DT3 transmitted from the communication control device 3a (NO in S31).

[0116] Specifically, the information receiving unit 311b waits, for example, until the communication control device 3a transmits policy information DT3 using the A1 interface defined in 3GPP.

[0117] Then, if policy information DT3 is received (YES in S31), the information receiving unit 311b stores the received performance information DT2 in the information storage area 330b, for example (S32).

[0118] [Measurement information storage processing in the second communication control device] Next, we will explain the process of storing measurement information DT1 (hereinafter also referred to as the measurement information storage process) within the communication control device 3b. Figure 14 is a flowchart illustrating the measurement information storage process.

[0119] As shown in Figure 14, the information receiving unit 311b waits until it receives, for example, measurement information DT1 transmitted from the base station device 1 (measurement information DT1 transmitted from the terminal device 2 via the base station device 1) (NO in S41).

[0120] Specifically, the information receiving unit 311b waits, for example, until the base station device 1 transmits the measurement information DT1 using the E2 interface specified in 3GPP.

[0121] Then, when the measurement information DT1 transmitted from the base station device 1 is received (YES in S41), the information receiving unit 311 stores the received measurement information DT1 in the information storage area 330b, for example (S42). A specific example of the measurement information DT1 will be described below.

[0122] [Measurement Details Specific Examples] Figure 24 illustrates a specific example of measurement information DT1. Specifically, Figure 24 illustrates a specific example of measurement information DT1 transmitted from base station device 1 corresponding to cell Ca.

[0123] As shown in Figure 24, the measurement information DT1 includes items such as "Cell," which contains information indicating each cell C, and "Reception Quality," which contains the reception quality of the signal transmitted from the base station device 1 corresponding to the adjacent cell C in each cell C.

[0124] Specifically, in the measurement information DT1 shown in Figure 24, for example, "Ca" is set as the "cell", "10 (dB)" is set as the "reception quality" corresponding to "Cd", "5 (dB)" is set as the "reception quality" corresponding to "Ce", and "3 (dB)" is set as the "reception quality" corresponding to "Cf".

[0125] In other words, the measurement information DT1 shown in Figure 24 indicates that, for example, the signal transmitted from base station device 1 corresponding to cell Ca, the signal transmitted from base station device 1 corresponding to cell Cd, the signal transmitted from base station device 1 corresponding to cell Ce, and the signal transmitted from base station device 1 corresponding to cell Cf were transmitted from terminal device 2 located in the competitive area Ac, which is capable of receiving each of these signals. In other words, the measurement information DT1 shown in Figure 24 indicates, for example, that cells Cd, Ce, and Cf exist as candidate handover destinations for terminal device 2 that transmitted the measurement information DT1.

[0126] [Value calculation process in the second communication control device] Next, we will explain the process of calculating various values ​​used to identify the HO destination cell C in the communication control device 3b (hereinafter also referred to as the value calculation process). Figure 15 is a flowchart illustrating the value calculation process.

[0127] As shown in Figure 15, the cell identification unit 313 waits, for example, until the second information generation timing occurs (NO in S51). The second information generation timing may be, for example, the timing when the measurement information DT1 transmitted from the base station device 1 (measurement information DT1 transmitted from the terminal device 2 via the base station device 1) is received in S41.

[0128] Then, when the second information generation timing arrives (YES in S51), the cell identification unit 313 identifies the competition area A based on the measurement information DT1 received in S41, for example (S52).

[0129] Specifically, the measurement information DT1 described in Figure 24 includes information about cells Ca, Cd, Ce, and Cf. Therefore, if the measurement information DT1 received in S41 is the measurement information DT1 described in Figure 24, the cell identification unit 313 identifies, for example, the competition area Ac.

[0130] Next, the cell identification unit 313 identifies, for example, the cell C (hereinafter also called the best cell C) with the highest reception quality at the terminal device 2 that transmitted the measurement information DT1 received in S41, based on the measurement information DT1 received in S41 (S53).

[0131] Specifically, the measurement information DT1 described in Figure 24 indicates, for example, that among cell Cd, cell Ce, and cell Cf, cell Cd has the highest reception quality. Therefore, if the measurement information DT1 received in S41 is the measurement information DT1 described in Figure 24, the cell identification unit 313 identifies cell Cd as the best cell C.

[0132] The cell identification unit 313 may, for example, generate aggregated information DT4 (hereinafter also referred to as aggregated information DT4a) which includes the aggregated results of the processing in S53. The cell identification unit 313 may, for example, store the generated aggregated information DT4a in the information storage area 330b. A specific example of aggregated information DT4a will be described below.

[0133] [Specific examples of aggregated information (1)] Figure 25 illustrates a specific example of aggregated information DT4a. Specifically, Figure 25 illustrates a specific example of aggregated information DT4a corresponding to measurement information DT1 transmitted from base station equipment 1 corresponding to cell Ca. Hereafter, the competition areas Aa, Ab, and Ac described in Figure 3 will be simply referred to as Aa, Ab, and Ac, respectively.

[0134] The aggregated information DT4a shown in Figure 25 includes, for example, the items "Competitive Area," which is where the competitive area A identified in S52 is set, and "Number of Received," which indicates the number of measurement information DT1 transmitted from terminal device 2 located in competitive area A identified in S52 (number of received data). Furthermore, the aggregated information DT4a shown in Figure 25 includes, for example, the items "Adjacent Cell," which includes information indicating the adjacent cell C to the cell C where terminal device 2 is located among the cells C forming competitive area A identified in S52, and "Best Cell Count," which indicates the number of times each cell C was identified as the best cell C in S53.

[0135] Specifically, the information in the first row of the aggregated information DT4a shown in Figure 25 is as follows: for example, "Aa" is set as the "competition area", "10000" is set as the "number of received", "Cb" and "Cc" are set as the "adjacent cells", "9000" is set as the "number of best cells" corresponding to "Cb", and "1000" is set as the "number of best cells" corresponding to "Cc".

[0136] Furthermore, the information in the second row of the aggregated information DT4a shown in Figure 25 is, for example, set as "Ab" for "Competitive Area", "5000" for "Number of Received", "Cc" and "Cd" for "Adjacent Cells", "1000" for the "Best Cell Count" corresponding to "Cc", and "4000" for the "Best Cell Count" corresponding to "Cd".

[0137] Furthermore, the information in the third row of the aggregated information DT4a shown in Figure 25 is as follows: for example, "Ac" is set as the "competition area," "5000" is set as the "number of received cells," "Cd," "Ce," and "Cf" are set as the "adjacent cells," "2000" is set as the "number of best cells" corresponding to "Cd," "1800" is set as the "number of best cells" corresponding to "Ce," and "1200" is set as the "number of best cells" corresponding to "Cf."

[0138] Returning to Figure 15, the cell identification unit 313 calculates, for example, the best cell rate for the competitive area A identified in S52 (S54). The best cell rate is, for example, the ratio of the number of best cells in each of the adjacent cells C that make up competitive area A to the total number of best cells in competitive area A.

[0139] Specifically, in the third row of the aggregated information DT4a shown in Figure 25, for example, "2000" is set as the "best cell count" corresponding to "Cd", "1800" is set as the "best cell count" corresponding to "Ce", and "1200" is set as the "best cell count" corresponding to "Cf". Furthermore, in the third row of the aggregated information DT4a shown in Figure 25, "5000" is set as the "number received". Therefore, in this case, the cell identification unit 313 identifies 40(%) as the best cell rate corresponding to cell Cd, calculated by dividing "2000", which is set as the "best cell count" corresponding to "Cd", by "5000", which is set as the "number received". Also, in this case, the cell identification unit 313 identifies 36(%) as the best cell rate corresponding to cell Ce, calculated by dividing "1800", which is set as the "best cell count" corresponding to "Ce", by "5000", which is set as the "number received". Furthermore, the cell identification unit 313 identifies 24(%) as the best cell rate corresponding to cell Cf, for example, by dividing the "1200" set as the "number of best cells" corresponding to "Cf" by the "5000" set as the "number of received cells".

[0140] Furthermore, as shown in Figure 25, the cell identification unit 313 may, for example, set the processing result of S54 into the aggregated information DT4a.

[0141] Specifically, the aggregated information DT4a may have an item called "Best Cell Rate," which, for example, sets the best cell rate calculated in S54, as shown in Figure 25. The cell identification unit 313 may, for example, set "40(%)" as the "Best Cell Rate" corresponding to "Cd" in the third row, set "36(%)" as the "Best Cell Rate" corresponding to "Ce" in the third row, and set "24(%)" as the "Best Cell Rate" corresponding to "Cf" in the third row.

[0142] Returning to Figure 15, the cell identification unit 313 calculates, for example, the transmission power offset adjustment rate (hereinafter also called the transmission power offset adjustment rate) for the competition area A identified in S52, based on the best cell rate calculated in S54 (S55).

[0143] Specifically, in the third row of the aggregated information DT4a shown in Figure 25, for example, "40(%)" is set as the "best cell rate" corresponding to "Cd", "36(%)" is set as the "best cell rate" corresponding to "Ce", and "24(%)" is set as the "number of best cells" corresponding to "Cf". Furthermore, the third row of the aggregated information DT4a shown in Figure 25 indicates that, for example, among the "best cell rate" corresponding to "Cd", the "best cell rate" corresponding to "Ce", and the "number of best cells" corresponding to "Cf", the "best cell rate" corresponding to "Cd" is the highest. Therefore, in this case, the cell identification unit 313 identifies 1 as the transmit power offset adjustment rate corresponding to cell Cd. Furthermore, in this case, the cell identification unit 313 identifies 1.11 as the transmit power offset adjustment rate corresponding to cell Ce, for example, which is calculated by dividing the "40(%)" set as the "best cell rate" corresponding to "Cd" by the "36(%)" set as the "best cell rate" corresponding to "Ce". Furthermore, the cell identification unit 313 identifies 1.66 in this case, for example, as the transmit power offset adjustment rate corresponding to cell Cf, which is calculated by dividing the "40(%)" set as the "best cell rate" corresponding to "Cd" by the "24(%)" set as the "best cell rate" corresponding to "Cf".

[0144] Furthermore, as shown in Figure 25, the cell identification unit 313 may, for example, set the processing result of S55 into the aggregated information DT4a.

[0145] Specifically, the aggregated information DT4a may have an item called "Transmit Power Offset Adjustment Rate," which, for example, sets the transmit power offset adjustment rate calculated in S55, as shown in Figure 25. The cell identification unit 313 may, for example, set "1" as the "Transmit Power Offset Adjustment Rate" corresponding to "Cd" in the third row, set "1.11" as the "Transmit Power Offset Adjustment Rate" corresponding to "Ce" in the third row, and set "1.66" as the "Transmit Power Offset Adjustment Rate" corresponding to "Cf" in the third row.

[0146] Returning to Figure 15, the cell identification unit 313 calculates, for example, the transmission power offset adjustment value (hereinafter also called the transmission power offset adjustment value) for the competition area A identified in S52, based on the transmission power offset adjustment rate calculated in S55 (S56).

[0147] Specifically, in the third row of the aggregated information DT4a shown in Figure 25, for example, "1" is set as the "transmit power offset adjustment rate" corresponding to "Cd", "1.11" is set as the "transmit power offset adjustment rate" corresponding to "Ce", and "1.66" is set as the "transmit power offset adjustment rate" corresponding to "Cf". Therefore, in this case, the cell identification unit 313 identifies +0 (dB), which is calculated by multiplying the natural logarithm of "1" set as the "transmit power offset adjustment rate" corresponding to "Cd" by 10, as the transmit power offset adjustment value corresponding to cell Cd. Also, in this case, the cell identification unit 313 identifies +0.4 (dB), which is calculated by multiplying the natural logarithm of "1.11" set as the "transmit power offset adjustment rate" corresponding to "Ce" by 10, as the transmit power offset adjustment value corresponding to cell Ce. Furthermore, the cell identification unit 313 identifies, for example, +2.2(dB) as the transmit power offset adjustment value corresponding to cell Cf, which is calculated by multiplying the natural logarithm of "1.66" set as the "transmit power offset adjustment rate" corresponding to "Cf" by 10.

[0148] In other words, the cell identification unit 313 identifies the transmission power offset adjustment value corresponding to each cell C such that, for example, the lower the best cell ratio calculated in S54, the larger the transmission power offset adjustment value. To put it another way, the cell identification unit 313 identifies the transmission power offset adjustment value corresponding to each cell C such that, for example, the lower the value indicated by the quality information (e.g., received power), the larger the transmission power transmitted from the base station device 1 corresponding to each cell C.

[0149] Specifically, the cell identification unit 313 identifies, for example, the cell C with the highest value set as "best cell rate" in the aggregated information DT4a. Then, the cell identification unit 313 identifies the transmission power offset adjustment value corresponding to each cell C, such that the transmission power offset adjustment value increases for each cell C, where the difference between the identified cell C and the corresponding best cell rate is larger.

[0150] Furthermore, as shown in Figure 25, the cell identification unit 313 may, for example, set the processing result of S56 into the aggregated information DT4a.

[0151] Specifically, the aggregated information DT4a may have an item called "Transmit Power Offset Adjustment Value," which, for example, sets the transmit power offset adjustment value calculated in S56, as shown in Figure 25. The cell identification unit 313 may, for example, set "+0" as the "Transmit Power Offset Adjustment Value" corresponding to "Cd" in the third row, set "+0.4" as the "Transmit Power Offset Adjustment Value" corresponding to "Ce" in the third row, and set "+2.2" as the "Transmit Power Offset Adjustment Value" corresponding to "Cf" in the third row.

[0152] Returning to Figure 15, the cell identification unit 313 calculates the competitive area load rate for the competitive area A identified in S52 based on the load information (cell load rate) calculated in S23 (S57). The competitive area load rate is, for example, the proportion of the cell load rate of each adjacent cell C that make up competitive area A to the total cell load rate of competitive area A.

[0153] Specifically, for example, if the cell load rate of cell Cd calculated in S23 (S111) is 90 (%), the cell load rate of cell Ce calculated in S23 (S111) is 20 (%), and the cell load rate of cell Cf calculated in S23 (S111) is 15 (%), then the sum of the cell load rates of cell Cd, cell Ce, and cell Cf (hereinafter also simply referred to as the sum of cell load rates) is 125 (%). Therefore, the cell identification unit 313 identifies 72 (%) as the "competition area" corresponding to "Cd," calculated by dividing the "90 (%)" set as the "cell load rate" corresponding to "Cd" by the sum of cell load rates. The cell identification unit 313 also identifies 16 (%) as the "competition area" corresponding to "Ce," calculated by dividing the "20 (%)" set as the "cell load rate" corresponding to "Ce" by the sum of cell load rates. Furthermore, the cell identification unit 313 identifies, for example, 12(%) as the "competition area" corresponding to "Cf," which is calculated by dividing the "15(%)" set as the "cell load rate" corresponding to "Cf" by the sum of the cell load rates.

[0154] The cell identification unit 313 may, for example, generate aggregated information DT4 (hereinafter also referred to as aggregated information DT4b) which includes the processing result of S57. The cell identification unit 313 may, for example, store the generated aggregated information DT4b in the information storage area 330b. A specific example of aggregated information DT4b will be described below.

[0155] [Specific examples of aggregated information (2)] Figure 26 illustrates a specific example of aggregated information DT4b. Specifically, Figure 26 illustrates a specific example of aggregated information DT4b corresponding to measurement information DT1 transmitted from base station device 1 corresponding to cell Ca.

[0156] The aggregated information DT4b shown in Figure 26 includes items such as "Competitive Area," where the competitive area A identified in S52 is set; "Adjacent Cell," where information indicating the adjacent cell C to the cell C where terminal device 2 is located among the cells C forming competitive area A identified in S52 is set; "Cell Load Rate," where the cell load rate calculated in S23 is set; and "Competitive Area Load Rate," where the competitive area load rate calculated in S57 is set.

[0157] Specifically, the information in the first row of the aggregated information DT4b shown in Figure 26 is as follows: for example, "Aa" is set as the "competition area", "Cb" and "Cc" are set as the "adjacent cells", "95(%)" is set as the "cell load rate" corresponding to "Cb", "40(%)" is set as the "cell load rate" corresponding to "Cc", "70.3(%)" is set as the "competition area load rate" corresponding to "Cb", and "29.7(%)" is set as the "competition area load rate" corresponding to "Cc".

[0158] Furthermore, the information in the second row of the aggregated information DT4b shown in Figure 26 is as follows: for example, "Ab" is set as the "competitive area," "Cc" and "Cd" are set as the "adjacent cells," "40(%)" is set as the "cell load rate" corresponding to "Cc," "90(%)" is set as the "cell load rate" corresponding to "Cd," "30.7(%)" is set as the "competitive area load rate" corresponding to "Cc," and "69.3(%)" is set as the "competitive area load rate" corresponding to "Cd."

[0159] Furthermore, the information in the third row of the aggregated information DT4b shown in Figure 26 is as follows: for example, "Ac" is set as the "competition area," "Cd," "Ce," and "Cf" are set as the "adjacent cells," "90(%)" is set as the "cell load rate" corresponding to "Cd," "20(%)" is set as the "cell load rate" corresponding to "Ce," "15(%)" is set as the "cell load rate" corresponding to "Cf," "72(%)" is set as the "competition area load rate" corresponding to "Cd," "16(%)" is set as the "competition area load rate" corresponding to "Ce," and "12(%)" is set as the "competition area load rate" corresponding to "Cf."

[0160] [Cell identification processing in the second communication control device] Next, we will explain the process of determining the HO destination cell C (hereinafter also referred to as the cell identification process) within the communication control device 3b. Figure 16 is a flowchart illustrating the cell identification process.

[0161] As shown in Figure 16, the cell identification unit 313 waits, for example, until the cell determination timing occurs (NO in S61). The cell determination timing may be, for example, the timing when the policy information DT3 transmitted from the communication control device 3a is received in S31.

[0162] Then, when it is time to determine the cell (YES in S61), the cell identification unit 313 determines, for example, whether the policy included in the policy information DT3 received in S31 indicates quality priority.

[0163] As a result, if the policy information DT3 received in S31 does not indicate quality priority, that is, if the policy information DT3 received in S31 indicates distribution priority, the cell identification unit 313 sorts, for example, the cells C corresponding to each competitive area A in order of competitive area load rate for each competitive area A (S63).

[0164] Then, the cell identification unit 313 identifies, for example, for each competitive area A, the cell C corresponding to each competitive area A that had the lowest competitive area load rate (S64).

[0165] Specifically, in the third row of the aggregated information DT4a shown in Figure 26, for example, "Ac" is set as the "conflict area," "72(%)" is set as the "conflict area load rate" corresponding to "Cd," "16(%)" is set as the "conflict area load rate" corresponding to "Ce," and "12(%)" is set as the "conflict area load rate" corresponding to "Cf." Therefore, if the aggregated information DT4b generated immediately before the timing of receiving the policy information DT3 in S31 is the aggregated information DT4a shown in Figure 26, the cell identification unit 313 identifies cell Cf as the cell C with the smallest conflict area load rate among the cells C corresponding to conflict area Ac.

[0166] On the other hand, if the policy information DT3 received in S31 indicates quality priority, the cell identification unit 313 sorts, for example, the cells C corresponding to each competition area A in order of received quality for each competition area A (S65).

[0167] Then, the cell identification unit 313 identifies, for example, for each competition area A, the cell C corresponding to each competition area A that had the highest value indicating reception quality (S66).

[0168] Specifically, in the measurement information DT1 shown in Figure 24, for example, "Ca" is set as the "cell", "10 (dB)" is set as the "reception quality" corresponding to "Cd", "5 (dB)" is set as the "reception quality" corresponding to "Ce", and "3 (dB)" is set as the "reception quality" corresponding to "Cf". Therefore, if the measurement information DT1 received immediately before the timing of receiving policy information DT3 in S31 is the measurement information DT1 shown in Figure 24, the cell identification unit 313 identifies cell Cd as the cell C with the highest reception quality value among the cells C corresponding to the conflict area Ac.

[0169] Next, the cell identification unit 313 sequentially references the cells C sorted in S63 or S65, in other words, sequentially references the cells C identified in S64 or S66, and identifies the cell C whose cell load rate corresponding to each cell C is the first to fall below the reference value corresponding to each cell C as the HO target cell C (S67).

[0170] Specifically, in the third row of the aggregated information DT4b shown in Figure 26, for example, "Ac" is set as the "competition area," "90(%)" is set as the "cell load rate" corresponding to "Cd," "20(%)" is set as the "cell load rate" corresponding to "Ce," and "15(%)" is set as the "cell load rate" corresponding to "Cf." Therefore, if the aggregated information DT4b generated immediately before the timing of receiving the policy information DT3 in S31 is the aggregated information DT4b shown in Figure 26, and the policy included in the policy information DT3 received in S31 indicates quality priority, the cell identification unit 313 will refer to the "cell load rate" corresponding to "Cd," the "cell load rate" corresponding to "Ce," and the "cell load rate" corresponding to "Cf" in this order. Here, the policy information DT3 shown in Figure 23 has, for example, "80(%)" set as the "reference value" corresponding to "Cd", "75(%)" set as the "reference value" corresponding to "Ce", and "70(%)" set as the "reference value" corresponding to "Cf". Therefore, if the policy information DT3 received in S31 is the policy information DT3 shown in Figure 23, the cell identification unit 313 determines, for example, that the "cell load rate" corresponding to "Cd", which is "90(%)", is not lower than the "reference value" corresponding to "Cd", which is "80(%)", and that the "cell load rate" corresponding to "Ce", which is "20(%)", is lower than the "reference value" corresponding to "Ce", which is "75(%)", and identifies cell Ce as the cell C (HO destination cell C) whose cell load rate first falls below the reference value.

[0171] Furthermore, the power calculation unit 314 identifies, for example, the transmission power offset adjustment value corresponding to the cell identified in S67 (S68).

[0172] Specifically, in the third row of the aggregated information DT4a shown in Figure 25, for example, "Ac" is set as the "competition area," "+0 (dB)" is set as the "transmit power offset adjustment value" corresponding to "Cd," "+0.4 (dB)" is set as the "transmit power offset adjustment value" corresponding to "Ce," and "+2.2 (dB)" is set as the "transmit power offset adjustment value" corresponding to "Cf." Therefore, if the cell C identified in S67 is cell Ce, the cell identification unit 313 identifies, for example, "+0.4 (dB)" which is set as the "transmit power offset adjustment value" corresponding to "Ce."

[0173] Subsequently, the power calculation unit 314 calculates the transmission power from the base station device 1 corresponding to cell C identified in S67 by, for example, using the transmission power offset adjustment value identified in S68 (S69).

[0174] Specifically, if the reference value for the transmit power corresponding to cell Ce is "+3.0(dB)", the cell identification unit 313 calculates "+3.4(dB)" by adding, for example, "+0.4(dB)", which is set as the "transmit power offset adjustment value" corresponding to "Ce", to "+3.0(dB)". Then, the power calculation unit 314 determines the calculated "+3.4(dB)" as the transmit power from the base station device 1 corresponding to cell Ce.

[0175] Furthermore, if the calculated transmission power (transmission power from base station device 1 corresponding to cell Ce) exceeds a predetermined upper limit (hereinafter also simply referred to as the upper limit), the power calculation unit 314 may, for example, determine the transmission power from base station device 1 corresponding to cell Ce to be the upper limit.

[0176] [Information transmission processing in the second communication control device] Next, we will explain the process in the communication control device 3b that transmits information indicating the processing result in the cell identification process (hereinafter also referred to as result information) to the base station device 1 (hereinafter also referred to as the information transmission process). Figure 17 is a flowchart illustrating the information transmission process.

[0177] As shown in Figure 17, the information transmission unit 315b waits, for example, until the information transmission timing is reached (NO in S71). The information transmission timing may be, for example, the timing after the cell identification process has been performed.

[0178] Then, when it is time to transmit information (YES in S71), the information transmission unit 315b generates result information that includes, for example, information indicating the HO destination cell C identified in S67 and information indicating the transmission power calculated in S69 (S72).

[0179] Subsequently, the information transmission unit 315b transmits the result information generated in S72 to the base station device 1 (the base station device 1 corresponding to the policy information DT3 received in S31) (S73).

[0180] As a result, the base station device 1 that transmitted the policy information DT3 can perform a handover of terminal devices 2 located in the cell C corresponding to its own device by, for example, referring to the result information transmitted from the communication control device 3. Specifically, the base station device 1 that transmitted the policy information DT3 can perform a handover of terminal devices 2 located in the cell C corresponding to its own device by, for example, sending and receiving necessary information with the base station device 1 corresponding to the HO destination cell C indicated by the result information transmitted from the communication control device 3.

[0181] Furthermore, in S72, the information transmission unit 315b may generate result information that includes, for example, the transmission power offset adjustment value specified in S68, either in place of, or together with, the transmission power calculated in S69.

[0182] As described above, the communication control device 3 in this embodiment receives, for example, quality information indicating the communication quality and load information indicating the communication load for each of the target cell C and a plurality of adjacent cells C from the base station device 1. Then, for example, for each of the plurality of adjacent cells C, the communication control device 3 calculates a reference value that indicates the upper limit of the load information for which the quality information in each adjacent cell C satisfies the first condition, based on the quality information and load information corresponding to each adjacent cell C.

[0183] Next, the communication control device 3 in this embodiment identifies, for example, one or more adjacent cells C from among a plurality of adjacent cells C whose load information at a predetermined timing is below a reference value, and based on the quality information corresponding to the identified one or more adjacent cells C, identifies one of the adjacent cells C as the HO destination cell C on which the terminal device 2 located at the target cell C will perform a handover at a predetermined timing. After that, the communication control device 3 in this embodiment transmits, for example, information indicating the identified HO destination cell C to the base station device 1 corresponding to the target cell C.

[0184] In other words, the communication control device 3 in this embodiment selects, for example, the adjacent cell C (HO destination cell C) to which the terminal device 2 will hand over in the competition area A from among adjacent cells C that can be determined to be capable of maintaining the minimum necessary communication quality.

[0185] As a result, the communication control device 3 in this embodiment can, for example, perform load balancing between each base station device 1 while suppressing quality degradation at the terminal device 2.

[0186] The policy information DT3 transmitted from the communication control device 3a to the communication control device 3b using the A1 interface may be transmitted in the format shown in Figure 27, for example.

[0187] Furthermore, the result information transmitted from the communication control device 3b to the base station device 1 using the E2 interface may be transmitted in the format shown in Figure 28, for example. Specifically, in the example shown in Figure 28, the "RAN Parameter Value" in the "List of RAN parameters[0]" of the "RIC Control Message" may be set to, for example, a value indicating the HO destination cell C identified in S67. Also, in the example shown in Figure 28, the "RAN Parameter Value" in the "List of RAN parameters[1]" of the "RIC Control Message" may be set to, for example, the transmit power offset adjustment value identified in S68.

[0188] The above embodiments can be summarized as follows:

[0189] (Note 1) An information receiving unit that receives quality information indicating the communication quality and load information indicating the communication load for each of a specific cell and several adjacent cells from the base station equipment, A cell identification unit identifies one of the plurality of cells as the first cell on which a terminal device located in the specific cell will perform a handover, based on the load information and quality information for each of the plurality of cells at a predetermined timing, A communication control device comprising: an information transmission unit that transmits information indicating the identified first cell to the base station device.

[0190] (Note 2) In Appendix 1, Furthermore, for each of the plurality of cells, there is a reference calculation unit that calculates a reference value for quality information that indicates the lower limit of the quality information that satisfies the first condition in each cell, or a reference value for load information that indicates the upper limit of the load information that satisfies the first condition in each cell, based on the quality information and load information corresponding to each cell. The communication control device is characterized in that the cell identification unit identifies the first cell based on the reference value of the quality information or the reference value of the load information.

[0191] (Note 3) In Appendix 2, The communication control device is characterized in that the cell identification unit identifies, among the plurality of cells, a cell in which the quality information at a predetermined timing exceeds a standard value for the quality information or the load information at a predetermined timing falls below a standard value for the load information as the first cell.

[0192] (Note 4) In Appendix 1, The communication control device is characterized in that the cell identification unit identifies the cell among the plurality of cells whose value indicated by the quality information at the predetermined timing is the maximum as the first cell.

[0193] (Note 5) In Appendix 1, The communication control device is characterized in that the cell identification unit identifies, among the plurality of cells, a cell whose load information at a predetermined timing satisfies a second condition as the first cell.

[0194] (Note 6) In Appendix 5, The communication control device is characterized in that the cell identification unit identifies the cell among the plurality of cells whose value indicated by the load information at the predetermined timing is the smallest as the first cell.

[0195] (Note 7) In Appendix 1, Furthermore, the communication control device is characterized by having a power calculation unit that calculates the transmission power to the terminal device in the first cell according to the quality information in the first cell.

[0196] (Note 8) In Appendix 7, The power calculation unit, Among the aforementioned multiple cells, identify the second cell whose value indicated by the quality information is the largest, A communication control device characterized by calculating the transmission power in the first cell such that the greater the difference between the value indicated by the quality information corresponding to the first cell and the value indicated by the quality information corresponding to the second cell, the greater the increase in the transmission power in the first cell.

[0197] (Note 9) The base station equipment receives quality information indicating the communication quality for a specific cell and several adjacent cells, and load information indicating the communication load. Based on the load information and quality information for each of the plurality of cells at a predetermined timing, one of the plurality of cells is identified as the first cell on which a terminal device located in the specific cell at the predetermined timing will perform a handover. Information indicating the identified first cell is transmitted to the base station device. A communication control program characterized by having a computer perform the processing.

[0198] (Note 10) In Appendix 9, Furthermore, the transmission power to the terminal device in the first cell is calculated according to the quality information in the first cell. A communication control program characterized by having a computer perform the processing.

[0199] (Note 11) The base station equipment receives quality information indicating the communication quality for a specific cell and several adjacent cells, and load information indicating the communication load. Based on the load information and quality information for each of the plurality of cells at a predetermined timing, one of the plurality of cells is identified as the first cell on which a terminal device located in the specific cell at the predetermined timing will perform a handover. Information indicating the identified first cell is transmitted to the base station device. A communication control method characterized in that a computer performs the processing.

[0200] (Note 12) In Appendix 11, Furthermore, the transmission power to the terminal device in the first cell is calculated according to the quality information in the first cell. A communication control method characterized in that a computer performs the processing. [Explanation of Symbols]

[0201] 1: Base station equipment 2: Terminal equipment 3: Communication control device 3a: Communication control device 3b: Communication control device 10: Wireless communication system 101: CPU 102: Memory 103: Communication circuit 104: Storage device 105: Bus 106: Antenna 110: Program 130: Information storage area 201: CPU 202: Memory 203: Communication circuit 204: Storage device 205: Bus 206: Antenna 210: Program 230: Information storage area 301: CPU 302: Memory 303: Communication circuit 304: Storage device 305: Bus

Claims

1. An information receiving unit that receives quality information indicating the communication quality and load information indicating the communication load for each of a specific cell and several adjacent cells from the base station equipment, A cell identification unit identifies one of the plurality of cells as the first cell on which a terminal device located in the specific cell will perform a handover, based on the load information and quality information for each of the plurality of cells at a predetermined timing, A communication control device comprising: an information transmission unit that transmits information indicating the identified first cell to the base station device.

2. In claim 1, Furthermore, for each of the plurality of cells, there is a reference calculation unit that calculates a reference value for quality information that indicates the lower limit of the quality information that satisfies the first condition in each cell, or a reference value for load information that indicates the upper limit of the load information that satisfies the first condition in each cell, based on the quality information and load information corresponding to each cell. The communication control device is characterized in that the cell identification unit identifies the first cell based on the reference value of the quality information or the reference value of the load information.

3. In claim 2, The communication control device is characterized in that the cell identification unit identifies, among the plurality of cells, a cell in which the quality information at a predetermined timing exceeds a standard value for the quality information or the load information at a predetermined timing falls below a standard value for the load information as the first cell.

4. In claim 1, The communication control device is characterized in that the cell identification unit identifies the cell among the plurality of cells whose value indicated by the quality information at the predetermined timing is the maximum as the first cell.

5. In claim 1, The communication control device is characterized in that the cell identification unit identifies, among the plurality of cells, a cell whose load information at a predetermined timing satisfies a second condition as the first cell.

6. In claim 5, The communication control device is characterized in that the cell identification unit identifies the cell among the plurality of cells whose value indicated by the load information at the predetermined timing is the smallest as the first cell.

7. In claim 1, Furthermore, the communication control device is characterized by having a power calculation unit that calculates the transmission power to the terminal device in the first cell according to the quality information in the first cell.

8. In claim 7, The power calculation unit, Among the aforementioned multiple cells, identify the second cell whose value indicated by the quality information is the largest, A communication control device characterized by calculating the transmission power in the first cell such that the greater the difference between the value indicated by the quality information corresponding to the first cell and the value indicated by the quality information corresponding to the second cell, the greater the increase in the transmission power in the first cell.

9. The base station equipment receives quality information indicating the communication quality for a specific cell and several adjacent cells, and load information indicating the communication load. Based on the load information and quality information for each of the plurality of cells at a predetermined timing, one of the plurality of cells is identified as the first cell on which a terminal device located in the specific cell at the predetermined timing will perform a handover. Information indicating the identified first cell is transmitted to the base station device. A communication control method characterized in that a computer performs the processing.

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